Descriptive epidemiological study on patients with movement disorders, with emphasis on Parkinson’s disease

ABSTRACT BACKGROUND: Knowing the epidemiological profile is relevant for improving healthcare practices. Movement disorders are neurological disorders characterized by the presence of involuntary movements. They have a negative impact on patients’ quality of life. OBJECTIVES: To outline the frequencies of the different diagnoses seen among patients, along with their demographic characteristics, at a hospital in São Paulo (SP), Brazil, and to highlight the clinical aspects of those with Parkinson’s disease. DESIGN AND SETTING: Retrospective descriptive epidemiological analysis at a specialized outpatient clinic in a state public hospital in São Paulo. METHODS: Patients treated at this clinic over a four-year period were analyzed. Diagnoses, demographic variables and associations with clinical aspects of Parkinson’s disease were evaluated. RESULTS: Out of the 680 medical records analyzed, 58.4% related to females. Most patients were over 60 years of age, white, married and teachers. The most frequent diagnosis was Parkinson’s disease, followed by essential tremor and dystonia. Parkinson’s disease presented in the mixed clinical form; the most common initial symptom was tremor. The akinetic-rigid clinical form occurred in younger individuals and mostly presented with postural instability and freezing of gait in the early years of disease. CONCLUSIONS: Parkinson’s disease, essential tremor and dystonia were the most frequent diagnoses. Characteristics like sex, frequency of other pathological conditions and the clinical and demographic aspects of Parkinson’s disease were consistent with the data in the relevant literature.

Progressive supranuclear palsy is considered to be the second most common form within the range of parkinsonian syndromes. Its incidence is approximately 5.3 cases per 100,000 people between 50 and 99 years old, and its prevalence ranges from 4.9 to 6.5/100,000. 18 Another example of parkinsonian syndrome is MSA, with an estimated incidence of 0.6 cases per 100,000 people, and a prevalence of 1.86-4/100,000, although there are few published studies on this. 15,19 Additionally, several other movement disorder-related diagnoses exist, thus highlighting the importance of evaluating their behavior.
These data are necessary for evaluating neurological institutions and services, and are important for identifying risk factors and geographical differences that might influence the development of treatment strategies. Knowledge of the characteristics and prevalence of diagnoses in this environment is required, in order to make comparisons with studies published previously.

OBJECTIVE
The objective of this study was to outline the frequencies of the different diagnoses seen among patients, along with their demographic characteristics, at the movement disorders outpatient clinic of a state public hospital, in São Paulo (SP), Brazil, and to highlight the clinical aspects of those with Parkinson's disease.

METHODS
This study consisted of a retrospective descriptive epidemiological review of data obtained from the medical records of patients seen at the neurology outpatient clinic specializing in movement disorders in a state public hospital, in São Paulo, Brazil. The medical records were searched based on a survey of patients with scheduled appointments who were seen at the movement disorders outpatient clinic. The analysis period comprised four years, starting from December 2009, when an electronic appointment scheduling system was implemented. The data were collected after the study protocol had been approved by an Internal Review Board (Ethics Committee) on May 13, 2014 (number 668.444/ CAAE: 305294 14.6.0000.5463) and had been authorized by the person in charge of the Medical Archive and Statistics Service (SAME).
Analysis on the medical records was previously authorized and scheduled as a maximum number of 20 medical records per day.
The records were analyzed individually in the medical file sector of the state public hospital, by one of the doctors responsible for this research. The study exclusively included patients who had been diagnosed with movement disorders.
The patients' diagnoses were recorded from the medical records.
The clinical evolution of the anamnesis and neurological examination were analyzed based on the diagnostic criteria. This information was described by neurology specialists in the movement disorder department. The entire procedure was supervised by chief neurologists.
The following demographic data were collected: age, sex, skin color, profession and marital status. In addition, correlations of the following relationships were assessed: "clinical diagnosis versus age"; and "clinical diagnosis versus sex".
Considering that the most frequent etiology would be Parkinson's disease, the following clinical characteristics were evaluated: initial symptoms, clinical form of the disease, freezing of gait and postural instability within the first five years of the disease. In addition, the following clinical correlations were considered: "clinical form versus age"; and "clinical form versus freezing of gait and postural instability".
The retrospective nature of this study was characterized as a limitation, considering that there was therefore a possibility of missing information. It is important to highlight that when information was not explicitly reported, these data were classified as not described (ND). Patients who did not have a defined etiological diagnosis due to lack of follow-up at the clinic or insufficient information were classified as "unspecified".
The data were expressed as absolute and relative frequencies for United States) was used in all analyses and the confidence level was set at 95%, i.e. a P-value < 0.05 was considered significant. It is important to note that, when the total number of cases evaluated that were described as "ND" was less than 10%, these were not considered in the study because they were not statistically significant.

RESULTS
Out of the 790 medical records analyzed, 680 were selected because they involved a diagnosis of movement disorders. Of these, 277 records included a diagnosis of Parkinson's disease. Thus, in order to demonstrate the analysis more clearly, the results are presented in two stages: (1) Parkinson's disease analysis; and (2) diagnoses of other movement disorders.

Parkinson's disease
We observed higher occurrence of the mixed clinical form of Parkinson's disease, which was present in 77.6% of all of these patients. The tremulous (TREM) and akinetic-rigid (AR) forms accounted for 18.4% of the case, and the other 4% of the medical records of Parkinson's disease did not specify the form. The most common initial symptom reported by the patient was tremor. It is important to emphasize that the diagnoses of postural instability and freezing of gait were not present in the first five years of follow-up, as described in Table 1.
The Parkinson's disease analysis showed that 66.7% of the patients above 61 years of age were diagnosed with the mixed form, and 71.4% of the patients below 61 years were diagnosed with the AR form. In 46.1 of the patients with the TREM form, the onset was when they were above 71 years old.   Table 2 shows that there was an association between early diagnosis and the AR form. We found that the older the patient was at diagnosis, the greater the probability of occurrence of the mixed and TREM forms was.
No individual with the TREM form in our sample presented postural instability and freezing of gait within the first five years of the disease. This characteristic was also observed in most patients with the mixed form. Furthermore, there was higher relative frequency of instability and freezing of gait among individuals with the AR form, thus indicating less favorable conditions for those patients.
The results from this analysis were compared with studies in the literature. This demonstrated that similar methodologies had been used to study Parkinson's disease in different parts of the world. The frequencies of occurrence described in previously published reports 5,6,11,14 suggested that Parkinson's disease was the most common cause of movement disorders in the entire population studied, which was consistent with the results from our analysis. However, an increasing number of secondary and atypical diagnoses of parkinsonism exist and need to be considered.
Consequently, an analysis of other movement disorder diagnoses is presented in the following section, in detail.

Analysis on other movement disorder diagnoses
The results from the analysis on the data collected during the study period showed that the most frequent diagnoses were Parkinson's disease (40.7%), essential tremor (15.4%) and dystonia (13.1%). The remaining diagnoses accounted for 33.6% of the cases. The frequencies of syndromic and etiological diagnoses of movement disorders are described in Table 3. The pattern shown in were diagnosed with drug-induced (n = 11) and vascular (n = 8) secondary parkinsonism. Atypical parkinsonism had an incidence of 3.5%, consisting of Lewy body disease (LBD) (n = 4), multiple system atrophy (n = 4) and progressive supranuclear palsy (n = 4).
The second most frequent pathological condition documented in the present study was 97 cases of essential tremor, which is one of the most common diagnoses in neurology outpatient clinics, often surpassing the number of Parkinson's disease cases. Its worldwide prevalence is widely variable, with descriptions ranging from one to more than 200 cases per 1,000 individuals. 15 Other etiologies for tremor were found in 31.2% of the cases. These cases included the following types: unspecified (n = 26), drug-induced (n = 4), others represented by a specific writing task (n = 3), Holmes (n = 2), orthostatic (n = 1) and psychogenic (n = 8).
Dystonia, which had the highest incidence, is a frequent condition reported in most studies, 5,8 and was diagnosed in 89 cases in our study, all corresponding to primary dystonia. According to the published reports, the occurrence rate has not changed over the years. Siemers and Reddy 11 reported dystonia in 17% of their movement disorder cases, which was a higher prevalence than that of their tremor cases (12%).
In the present study, chorea was present in 2.4% of the cases, Huntington's disease accounted for 1% of the cases and other forms  (60 %) were more common in males. Parkinsonism had similar distribution between the male and female groups, as described in Table 5, which shows absolute and relative values.
The distribution of the diagnoses according to age group revealed a statistical difference between the groups listed. Parkinsonism was more frequent in the age groups above 60 years, while dystonia showed higher frequency in individuals aged 60 years or less. The other syndromes had uniform distribution, or were highly influenced by low sample sizes in the groups, e.g. the distribution of ataxia. These analyses are described in Table 5.

DISCUSSION
Neuroepidemiology aims to determine the presence of neurological diseases in the population and acts as an instrument for healthcare planning and improvement. This has undergone increasing changes due to increases in life expectancy. tremulous, akinetic-rigid and mixed. As indicated in this study, the mixed form is considered to be most frequent. This conclusion is corroborated by results found in other published studies. 14,28,29 In our study, the clinical forms were correlated with age, and we showed that most patients presenting the tremulous form (84.6%) were over 60 years of age, thus confirming the results of Pagano et al. 30 Approximately 71.4% of the patients with the akinetic-rigid form were diagnosed under the age of 60 years. Previous reports have demonstrated biological differences between the clinical forms of Parkinson's disease. 14,31 Resting tremor was reported in this study, in 60.3% of the patients at the onset of the disease. It is considered to be the most frequent initial symptom in the mixed and tremulous forms. 29 Delval et al. 32 showed that 27% of the patients analyzed in their study presented with a history of freezing of gait at the first evaluation, with a considerable increase observed eight years after the initial diagnosis. 33 Other published reports confirmed the results from this study, thus suggesting that freezing of gait occurs with higher frequency in the akinetic-rigid form of the disease. 32 As previously stated, the most frequent diagnosis in our study was Parkinson's disease. However, increasing numbers of cases of secondary and atypical parkinsonism cases are common. This result was found in a previously published study, 7 which showed that vascular parkinsonism was the second most  Hemifacial spasm is characterized by segmental facial myoclonus, which was the fourth most common diagnosis found in the present study. A previously published report by Batla et al. 34 showed that the incidence of this condition was 7% in India. Other surveys conducted in the cities of Barcelona and Madrid indicated that the incidence of hemifacial spasm was 1.8% and 5%, respectively. 5,10 Although hemifacial spasm is a common complaint in neurology outpatient clinics, its frequency does not differ significantly from that of other extrapyramidal diseases. 5 This pattern was also observed in a study by Fahn et al. 14 in the United States, which showed the same frequency of this pathological condition as found in the present study.
Our results for ataxia and chorea were similar to those in other published reports. 6,7,10,11 However, one study in Ethiopia reported that the prevalence of ataxia was more than twice that of chorea, even surpassing the rate of diagnosing dystonia. 6 These results suggest that there was a lack of uniformity in the data for making this diagnosis. in Japan and 15% in the United States. 38 In our study, SCA2 and SCA3 both had incidences of 12.5%. Despite the low frequency in our study, these etiologies are recognized as the most frequent types. 39 Similar results were also found in other studies. [38][39][40] The diagnoses of tics and tardive dyskinesia were infrequent in our study, and also infrequent in other movement disorder outpatient clinics. 5, 6,11 Fahn et al. 14